Movies about movies—and Hollywood in general—are like little nuggets of joy for people like me. They offer both a history lesson and a reward for being familiar with the movies and celebrities being portrayed. When it was announced that a film about the legendary screenwriter Dalton Trumbo was in the works, you can be assured that I got unnaturally giddy—even more so when Bryan Cranston was cast to portray him. Being the writer of classic movies like Spartacus, Roman Holiday, The Brave One, Trumbo’s life is one of controversy with his ties to the communist party; success with all the movies he delightfully wrote; and inspiration as he stands up for free speech and thought. Trumbo, directed by Jay Roach (Meet the Parents) tries to be all of these things at once, and the result ends up being an unfocused—yet utterly fascinating—look at a dark time in American—and Hollywood—history.

Trumbo is prominently saved by a wickedly entertaining performance from Cranston—and the rest of the cast for that matter—who gives us one of the most enjoyably watchable characters this year. He has a knife-sharp sense of humor that he delivers with a silver tongue, a sense of loyalty to his country, and a love for his family that never falters as he is condemned as a communist and sent to prison. It is an astounding performance, and the screenplay by John McNamara really caters to building him up and working to his strengths, and it works almost too well making it curious as to why the same time and attention wasn’t given to the rest of the film.

The problem with Trumbo is that it never has a sense of where it is going. It isn’t a traditional biopic in the manner that it covers only twenty years of Trumbo’s life, mostly the period revolving around the Red Scare, his blacklisting and imprisonment, and his sneaky comeback. But as many little threads are woven, characters come and go, and relationships get tested, the movie has no problem in creating interesting moments—it just lacks the drive and focus to really flesh out these narratives in a meaningful way.

For example, Trumbo’s relationship with his daughter—played later in the film by a splendid Elle Fanning—could be a movie in itself as she proves herself to be her father’s daughter. As he becomes so driven in his pursuits at getting his name back, his relationship with her suffers the most. Trumbo’s wife, Cleo—played by a wonderful and endearing Diane Lane—could have also been utilized more purely for the fact that Cranston and Lane share a highly indelible chemistry. These are just two of the many opportunities that the movie never explores to its fullest.

If Trumbo himself got a hold of the script, you can imagine the amount of stuff he could cut out of the movie to really tighten it up. Too many of the scenes don’t have much effect on the film, especially his time in prison—which is important, but doesn’t really introduce anything new other than exposition. The rest of the cast, which includes the likes of Helen Mirren as the gossipy former actress Hedda Hopper, Michael Stuhlberg, Louis C.K., and John Goodman, are all effective, even with Cranston ruling the show.

While Trumbo’s main character is a remarkably performed champion for the freedom of speech, the rest of the film bumbles along through its 125 minute story that is crucially missing the inspiration and power of the man being portrayed. Trumbo isn’t horrible, it’s actually quite fascinating and entertaining once you get past its scattered plot.